A102930 -id:A102930 - cp's OEIS frontend

A102632 Smallest k such that at least one of 2^k+/-prime(n) is prime.

0, 1, 1, 2, 1, 2, 1, 2, 3, 1, 4, 2, 1, 2, 5, 3, 1, 6, 2, 1, 4, 2, 7, 3, 2, 1, 2, 1, 2, 7, 2, 3, 1, 9, 1, 4, 4, 2, 5, 3, 1, 4, 1, 2, 1, 6, 4, 2, 1, 2, 3, 1, 4, 5, 9, 3, 1, 9, 2, 1, 6, 7, 2, 1, 2, 5, 4, 4, 1, 2, 16, 3, 4, 4, 2, 10, 3, 2, 3, 9, 1, 8, 1, 4, 2, 7, 3, 2, 1, 2, 5, 3, 2, 3, 2, 7, 5, 1, 6, 4, 4, 9, 3, 1

Offset: 1

Lei Zhou, Jan 20 2005

nonn

			For prime(2)=3, 2^1+3 = 5 is prime
For prime(18)=61, 2^6-61 = 3 is prime

Lei Zhou, Between 2^n and primes.

Cf. A102930, A102931, A094076, first occurrence in A103032.

f[n_] := Block[{k = 0, p = Prime[n]}, While[ Not[(2^k - p > 1 && PrimeQ[2^k - p]) || PrimeQ[2^k + p]], k++ ]; k]; Table[ f[n], {n, 104}] (* Robert G. Wilson v, Jan 22 2005 *)

More terms from Robert G. Wilson v, Jan 21 2005

A102010 Indices of primes in sequence defined by A(0) = 17, A(n) = 10*A(n-1) - 43 for n > 0.

Original entry on oeis.org

0, 1, 3, 13, 24, 31, 55, 61, 810, 811, 1083, 2532, 11923, 49551

Offset: 1

Klaus Brockhaus and Walter Oberschelp (oberschelp(AT)informatik.rwth-aachen.de), Dec 28 2004

Numbers n such that (110*10^n + 43)/9 is prime.
Numbers n such that digit 1 followed by n >= 0 occurrences of digit 2 followed by digit 7 is prime.
Numbers corresponding to terms <= 811 are certified primes.
a(15) > 10^5. - Robert Price, Jan 16 2015
a(15) > 2*10^5. - Tyler Busby, Feb 01 2023

			12227 is prime, hence 3 is a term.

Klaus Brockhaus and Walter Oberschelp, Zahlenfolgen mit homogenem Ziffernkern, MNU 59/8 (2006), pp. 462-467.

Makoto Kamada, Prime numbers of the form 122...227.
Index entries for primes involving repunits.

Cf. A000533, A002275, A102930.

a=17;for(n=0,1500,if(isprime(a),print1(n,","));a=10*a-43)

for(n=0,1500,if(isprime((110*10^n+43)/9),print1(n,",")))

a(n) = A102930(n) - 1.

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(13)-a(14) derived from A102930 by Robert Price, Jan 16 2015

cp's OEIS Frontend

A102632 Smallest k such that at least one of 2^k+/-prime(n) is prime.

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